According to M. Jones and J. Pierce in 1964, amino acid uptake occurs sequentially when Saccharomyces cerevisiae grows in a complex medium. whatever the individual concentration. The objective of the current work was to determine to what extent, under different conditions, the four previously defined amino acid families can still be distinguished. For this purpose. amino acid uptake was monitored during fermentation in the presence of one ale and two lager yeasts conducted at various scales (1-L tall EBC tubes and 1-L conical flasks) and temperatures (23 and 28degreesC). Industrial production (1-hL rectangular vessel) conducted with a co-culture of three ale yeasts was also investigated. A critical time (Tc), defined as the time it takes the amino acids of group A' (named A' in the Current work) to be totally consumed, emerged from all our experiments. This group coincides with the A class defined by M. Jones (aspartate, threonine. serine. glutamate. lysine, and arginine) plus methionine and minus arginine. Tc also corresponds with the beginning of consumption of an amino acid group (named C' in the current work) that includes only glycine and alanine. All other amino acids. defining the B' group, (named B' in the current work) are slowly and gradually taken up without any lag phase.